Hopes high for a ‘Super’ El Niño

The weather phenomenon could bring rain but also mudslides and drought to the different regions of the West.

 

El Niño is upon us and it’s shaping up to be a big one – so big that scientists have amused themselves coming up with new terms for the coming weather phenomenon. Bill Patzert of NASA coined the term “Godzilla El Niño.” Another meteorologist from the National Oceanic and Atmospheric Administration (NOAA) who loves kung fu compared it to famed martial arts star Bruce Lee.

El Niño, which is Spanish for “the baby,” is a weather phenomenon that occurs every two to seven years when the Pacific Ocean water west of Peru warms, throwing global weather patterns out of whack (think more storms, droughts and heat waves). 

This year, many global weather models are signaling that we’re in for a whopper of an El Niño. In fact, some indicate that we appear to be on track to experience one of the strongest El Niños on record. Still, Klaus Wolter, a climate scientist at the University of Colorado Boulder, cautions against getting too caught up in the hype. “There’s always a race for the biggest epithet,” he says. El Niños can vary in strength, and it’s impossible to know yet just how big a punch this one will deliver. The latest models show the current El Niño as the second strongest on record for this time of year (it typically peaks in winter), but some models have scaled back their predictions of a "Super" El Niño. That's not uncommon: Last year, the odds of a “Super” El Niño occurring diminished substantially — from close to 80 percent earlier in the summer down to 65 percent by August.

In short, nothing is guaranteed. But, if this year’s El Niño does live up to its name(s), here’s what the West can expect: 

California

With over 90 percent of the state in severe drought or worse, Californians are praying this year’s El Niño will deliver the kind of rain that occurred in 1998, the strongest El Niño ever recorded. February of that year brought 13.68 inches of rain to Los Angeles — about a year’s worth — and made it the wettest February since the city began record-keeping more than 130 years ago. That’s potentially good news for the drought, but in areas that have seen extensive wildfires, that kind of rain could bring devastating mudslides.

Just how much El Niño alleviates California’s drought will likely depend on its strength. As sea temperatures warm in the eastern Pacific, storms moving towards California pick up more moisture, which means more rain (and hopefully snow) dumped along the Sierra Mountains. “It’s like opening a valve,” Wolter says. But unless it’s a really strong El Niño, most of the precipitation will go to Southern California. That would help farmers in the parched Imperial Valley, but won’t do much for the overall water supply, since almost all the storage reservoirs lie in the northern part of the state. If, however, a “super” El Niño does hit, according to Wolter, “it’s like opening an out-of-control fire hose,” swinging back and forth wildly from the force of the water, potentially even drenching the northern part of the state.

In California, models show a strong correlation between very strong El Niños and wetter than normal weather. Weaker El Niños tend to be drier.
Klaus Wolter

Pacific Northwest

After a dry winter and a blistering summer, the Pacific Northwest is desperate for rain, but unlike California, Washington and Oregon are unlikely to benefit from this winter’s El Niño. Same deal for states east of them, like Idaho and Montana. Forecasts are calling for another low-snowpack year, putting more pressure on already stressed-out salmon, ski resorts, and hydropower that cities like Seattle depend on. Slightly more rain could arrive if El Niño turns into the big one because the “fire hose” effect could reach the more northern parts of the West Coast.

Southwest

In contrast to the Northwest, El Niño means good news for Arizona and New Mexico (though as the recent flash flood deaths in Utah reveal, heavy rain in desert areas can be dangerous too).  They’ll likely see a wet winter and spring. Similarly, in the southern Rockies, El Niño will tilt the odds in favor of a snowy winter, a boon to ski resorts that make up much of the region’s tourism economy. However, more central and northern parts of the Rockies, extending into Wyoming, will probably suffer relatively dry winters – until spring that is, when El Niño could deliver some mega-storms.

Overall, the prognosis is mixed for the fragile Colorado River Basin and its shrinking reservoirs. Decades of over-allocation and a 15-year warm spell have pushed Lake Mead just inches from unprecedented mandatory water restrictions. In general, the pattern of past El Niños does not correlate well with total runoff, says Wolter, since dry winters tend to cancel out wet springs. But as this year proved, a spring boost could give the Basin states some breathing room.

Note: this article has been corrected to reflect the fact that although some models have scaled back the odds of a "Super" El Niño, the drop from 80 percent to 65 percent occurred last year, not this year.

Sarah Tory is an editorial fellow at HCN.